Internal-combustion engine



Filed March 1 1928 2 Sheets-Sheet S W a m? J 1 n; a .u 2 gm, l w H m u ZMOOEHY. g M I 2\.OOO My a w 5 0 J m 0 w i I w m f 5 j m f g M W -7 I .Z: @1111 can Attorney Dec. 10, 1929.

P- LINDAHL ET AL INTERNAL COMBUSTION ENGINE Filed March 1928 2 Sheets-Sheet 2 I72 wen for;

Patented Dec. 10, 1929 UNITED STATES PATENT OFFICE inrnnnnn-oonnnsrron ENGINE Application filed March 1, 1928. Serial No. 258,296.

The present invention relates to an internal combustion engine of the two cycle type and has for its prime object to provide an exceedingly efficient construction forobtalning the maximum power with the minimum expenditure of fuel Another very important object of the mvention resides in the construction of a twocycle internal combustion engine having a pair of pistons therein one operating within the skirt of the other for thoroughly scavenging the burnt gases and utiliziing all the expansion energy thereof.

With the above and numerous other objects in view as will appear as the description proceeds, the invention resides 1n certain novel features of construction, and in the combination and arrangement of partsias will be hereinafter more fully described and 2 claimed. it

In the drawing:

a Figure 1 is a longitudinal sectionthrough the engine embodying the. features of my invention showing the pistons in one position, a

Figure 2 is a similar view showing the pistons in another position, and

Figure 3 is a transverse section taken substantially on the line 3--3 of Figure 1.

Referring to the drawing in detail it will be seen that the numeral 1 denotes a crank case and the numeral 2 a cylinder extending therefrom and communicating therewith.

. A crank shaft 3 is journaled in the crank case 1 suitable bearings '20 being provided for this purpose. A connecting rod 1 is engaged on one crank of the crank shaft while a connecting rod 4 is engaged with the other crank thereof. A piston 6 is slidable in the cylinder 2 and includes a cylindrical skirt 21 having an annular series of openings 22 intermediate the ends thereof. The headof the piston 6 is provided with a valve seat opening 23 having a spider extending inwardly and upwardly therefrom as at 2 1 for supporting a bearing 25 through which slides a valve stem 26 connected to a valve 16 seatable on the valve seat opening 23 and normally held seated by a spring 27 impinging against a stop 28 on the stem 26 and the spider structure 24:. The cylinder is provided with an annular series of intake ports 13 adjacent its upper end leading to a manifold 11 disposed about the cylinder and having an opening 29 for connection with a carbureter. The cylinder is provided with an annular series of exhaust openings 15 leading to an exhaust manifold 14 having an opening 30 for con nection with an exhaust pipe.

Inside the skirt 21 of the piston 6 there is slidably mounted an inner piston 5 which is provided with a semi-cylindrical skirt portion 31 with which the connectingrod 4: is engaged by means of a wrist pin 32. The connecting rod 4 is connected with the lower semi-cylindrical portion of the skirt 31 by the wrist pin 33. A cylinder head 10 is mounted on the upper end of the cylinder 2 being held in place in any suitable manner. The corded faces of the semi-cylindrical portions provide plain bearing surfaces for a portion of the stroke, in addition to the cylindrical bearing surfaces.

'Ihisengine is of the two-cycle type and when firing or explosion occurs the piston 5 moves downwardly and the piston 6 moves upwardly from the position shown in Figure 2, the mixture being ignited by spark plug 12. The piston 5 moves down and uncovers the exhaust port 15 and lets the burnt gases out. When the pressure in the explosion chamber 7 becomes less than the pressure in the intake chamber member 8, which is to be about twen' ty pounds for instance, when the outside piston 6 is at the top, the valve 16 will open and let in fresh gas into the explosion chain her 7 and force out the balance of the burnt gas thus thoroughly scavenging the chamber 7. When the pressure is equalized the valve 16 automatically closes through the tension of the spring 27 and the piston 6 starts down and the piston 5 starts up. When the piston 6 starts down it will create a vacuum in the chamber 8. When the intake ports 13 are uncovered by the piston 6 gas vapors will rush into the intake chamber through the openings 13 and manifold 10. The effect on the crank shaft will be that the piston 6 will pull up and the piston 5 will push down for causing rotation of the crank shaft. The intake ports the "spirit or scope of the invention as erein- 13 are disposed all around the cylinder except immediately adjacent the spark plug port.

The exhaust ports 15 are registered with by the ports 22 and the skirt 21 for exhausting and scavenging the burnt gases.

A spark plug 12 is incorporated in the skirt of the piston 6 and when it comes opposite to the plug 12 as is disclosed in Figure 2 the explosion takes place. 1 r 7 Any cooling system, not shown, may be uti: lized with this engine as will be quite ap-. parent to those skilled in this art. i i

It is thought that the construction, opera: tion, and advantages of this invention will now be'quite apparent tothose skilled in this art without a more detailed description there of, The present embodiment of the invention has been disclosed in detailmerelyby way of examplesincein actual practice it attains'the featuresof advantage enumerated as desirable inthe statementof the invention and the above description. It will be apparent that changes in the details of construction, and in thecombination and arrangement of parts may be resorted to without departin from after claimed or sacrificing any of its advantages. l

Having thus described our invention, what weclaim as new is:

1. In an :internal combustion engine of the two c ycle type, a crank case, a cylinder extending from theerank case, a crank shaft journaled inthe crank case, a piston slidable in the cylinder and having an elongated skirt 7 extending therefrom, said skirt being provided with an annular series-of openings, said;

cylinder being formed with an annularseries of openings with which the openings of the skirt are adapted to register, a connecting rod operatively connecting the skirt with the crank shaft, a second piston slidably mounted within the skirt, a semi-cylindrical skirt portion formed on said second piston, a connecting rod operatively connecting the second piston with the crank shaft, said cylinderbeing provided with an annular series of intake openings,:said first piston being provided with a check valve inthe head thereof opening inwardly thereof, spring means for normally holding the'check valve closed, a spark plug in the cylinder, the skirt of the first piston being provided with an opening to be brought into registry with the spark plug.

2. In an. internal combustion engine of the two cycle type, a crank case, a cylinder extending from the crank case, a crank shaft journaled in the crank case,a pistonfs'lida'ble inthe cylinder andhaving anelongated skirt extending therefrom, said 'sk-i rt being pro vided With'an'annular series of openings, said cylinder being formed with an annular serieso'f'openings with which the openings of the skirt are adapted to register, a connecting rodoperatively connecting the skirt with the spar- Pl s a h yiin emhe skirt of the first piston being provided with an opening to. be brought into registry with the spark plug, annular manifolds formed about the cylinder in communication with the exhaust and intake openings res )ectively.

3'. In an internal com ustion engine of the two-cycle type, a pair of pistons one slidable within the'other, one of said pistons formed with a semi-cylindrical skirt portion, means for igniting gas between the cylinder, the outer cylinder having a check valve in the head thereof openable inwardly and having a stem projecting outwardly from the first piston, a spring associated with the stem to normally hold the valve closed, a head on the cylinder with, a projection to accommodate the stem, said cylinder being provided with an annular series of intake openings and an annular series of exhaust openings, the skirt of the first piston being provided with an annular series of openings to register with the exhaust openings.

4. In an internal combustion engine of the two-cycle type, a pair of pistons one slidable within the other, one of said pistons formed with a semi-cylindrical skirt portion, means for ignitin gas between the cylinder, the outer cylinder having a check valve in the head thereof openable inwardly and having a stem projecting outwardly from the first piston, a spring associated with thestem to normally hold the valve closed, a head on the cylinder with a projection to accommodate the stem, said cylinder being provided with an annular series of intake openings and an annular series of exhaust opening, the skirt of the first piston being provided with an annular series of openings to register with the exhaust openings, a pair of manifolds formed about the cylinder one com nunicat-- 7 the stem, said cylinder being provided with an annular series of intake openings and an annular series of exhaust openings, the skirt of the first piston being provided with an annular series of openings to register with the exhaust openings, a pair of manifolds formed about the cylinder one communicating with the intake ports and the other communicating with the exhaust ports, a crank case on the cylinder, a crank shaft journaled therein, and connecting rods between the pistons and the crank shaft.

In testimony whereof we aflix our signatures.

, PETER LINDAHL. LAUREL DUNCAN. 

